The present invention relates to a method for testing semiconductor devices, and more particularly to a semiconductor-device inspecting apparatus for attaining high reliability and high yield and a method for inspecting electrical characteristics of semiconductor devices by efficiently inspecting the electrical characteristics of the semiconductor devices in the process of manufacturing semiconductor devices such as in probing inspection and burn-in inspection which is performed in a wafer state.
The process of manufacturing semiconductor devices such as ICs and LSIs is largely classified into a so-called earlier process up until the formation of integrated circuits on a silicon wafer surface and a so-called later process in which this silicon wafer is cut into individual chips which are then encapsulated in a resin, a ceramic or the like.
In these semiconductor devices, inspection of the electrical characteristics of each circuit is performed in a predetermined stage during the earlier process, and a determination of non-defective products and defective products is made in chip units.
The aforementioned electrical characteristic inspection can be largely classified into the probing inspection in which whether electrical continuity between circuits is good or bad is determined, the burn-in inspection in which failures are checked under acceleration by imparting thermal and electrical stresses to the circuits at a high temperature of 150xc2x0 C. or thereabouts, and the final inspection in which inspection is finally performed by high frequency. Particularly in the final inspection which is performed by high frequency, there has been a demand for an inspection system of high-speed operation in which inspection of high-speed devices is performed by ultra high frequency.
In all of the aforementioned various inspecting methods, their basic connecting means for connecting a subject wafer or a subject chip and an external inspection system are similar. Then, a method is adopted in which very small electrically conductive probes are mechanically pressed against respective electrode pads which are made of an aluminum alloy or other alloy, which are patterned on the subject wafer with pitches of several dozen to a hundred and several dozen microns, and which are several dozen to a hundred and several dozen microns square (xcexcm2) and about one micron (xcexcm) thick. For example, in a case where tungsten probes with tips having a curvature of 20 microns (xcexcm) or thereabouts are brought into contact with very small electrode pads made of aluminum to test electrical continuity, the probes are caused to slide on the pad surfaces to obtain electrical contact so as to break oxide films formed on the electrode pad surfaces. For this reason, large scars are formed on the pad surfaces after the inspection. In the future, in conjunction with the high integration of the semiconductor devices, a low-load inspection technique which does not cause damage to the electrode pads will be required in correspondence with a narrow-pitch inspection technique or the thin film electrode pads of the semiconductor devices.
As a conventional example of the probing inspection, a method disclosed in JP-A-1150863 is known. In this method, bridges with their both ends fixed to an upper surface of a board are formed, and probes are respectively formed on their centers, electrically conductive wiring being formed in such a manner as to extend from the respective probes.
In addition, a method disclosed in JP-A-8-75758 is also known. In this method, a probe is formed on a both-ends supported beam, and the probe is formed at a position orthogonally offset with respect to a longitudinal center line of the both-ends supported beam. It should be noted that this invention is used for a scanning probe microscope (SPM) and an information processing apparatus such as a recording and reproducing apparatus.
According to the above-described methods for inspecting semiconductor devices described in the related art, the following problems have been encountered.
With the former method, since a plurality of bridges are attached to the upper surface of the board, it is difficult to cope with products of narrow pitches. In addition, since the probe is formed at the center of the beam, if the probe is pressed against the electrode pad, the pressing force acts only in the vertical direction, so that it can be estimated that the probe is unable to brake an oxide film formed by alumina or the like and formed on the surface of the electrode pad formed of an aluminum material, with the result that the resistance value becomes large, making it impossible to obtain satisfactory continuity.
With the latter method, because of the position where the probe is formed and because the beam is formed of a separate member on a silicon board, the area for forming the probe becomes large, and much time and trouble is required for positioning the probe with high accuracy and fixing it. Hence, it can be estimated it is difficult to cope with the tendency toward formation of narrower pitches, and that the production yield is low. In addition, since two kinds of electrodes are formed on the beam to warp the beam, even if a plurality of probes are formed, the variation of the height of the probes will become large, so that it can be estimated that the probes cannot be formed at a fixed height, and the structure is complicated.
Further, with this method, since the number of probes provided is only one, and due to the fact that the probe is used in contact, and the method is not for use in the case where a plurality of probes are formed, it can be estimated that the structure is not such that, for example, the contact with electrode pads is assumed.
Accordingly, it is an object of the invention to realize a semiconductor inspecting apparatus which is capable of allowing probes to reliably come into contact with electrode pads formed on, for example, a semiconductor device for inspection at narrow pitches in the electrical characteristic inspection of the semiconductor device, and which is capable of increasing the probe life remarkably with a low pressing force and without forming unnecessary scars on the electrode pads, thereby overcoming the above-described numerous problems.
Another object of the invention is to provide a method for manufacturing a semiconductor inspecting apparatus and a method for inspecting a semiconductor device which are capable of improving the production yield, reducing the manufacturing cost, and consequently making it possible to obtain highly reliable semiconductor devices at low cost.
To attain the above objects, a structure adopted is such that in order to cause probes respectively formed on a plurality of beams formed on a first board of a plurality of electrical connection boards arranged in an inspecting apparatus to be individually brought into direct contact with a plurality of electrode pads of a semiconductor device for inspection so as to inspect the semiconductor device while establishing electrical connection therebetween, wherein each of the probes formed on the first board is formed substantially on a longitudinal center line of each beam and at a position offset from a point of application of a force of the beam, and wiring is connected continuously from the probe to a secondary electrode pad portion through an insulating layer.
It should be noted a structure is preferable in which a both-ends supported beam is used as each of the beams, and each of the probes is formed at a position offset from a longitudinal center of the both-ends supported beam toward one one longitudinal side of the both-ends supported beam. The probes which are brought into contact with electrode pads for inspection are capable of absorbing the variation of the height of the individual electrode pads and of establishing reliable contact with the electrode pads while scraping the surfaces of the electrode pads, thereby making it possible to obtain satisfactory contact resistance.
In addition, by adopting a structure such that a cantilever is used as each of the beams, and each of the probes is formed at a position offset in a direction perpendicular to a longitudinal center line of the cantilever, inclination may be added in the rotating direction in a case where the probe is brought into contact with the electrode pad. It should be noted that a predetermined angle may be provided for the surface of the center beam of the tip of each probe.
By adopting a structure such that each of the probes has an inclination of 45 degrees or more with respect to a vertical direction so as to be brought into contact with the electrode pad, the effect of scraping the surface of the electrode pad is enhanced, and it is possible to obtain satisfactory contact resistance. Hence, since satisfactory contact resistance can be obtained under a low pressing force, scars imparted to the electrode pads are shallow.
In addition, a manufacturing process is adopted which comprises the steps of: forming probes of silicon; patterning a compensation pattern for the probes by using a photolithographic process; forming the probes by wet etching; forming multilayer mask patterns by using the photolithographic process; processing reverse sides of the beams by wet etching; and forming the first board by using means for forming the beams by dry etching.
This manufacturing process is a process to process grooves with a high aspect ratio by dry etching after effecting processing by using wet etching excelling in mass productivity so as to allow the probes arranged at narrow pitches or at a high density to be separated at the individual beams.
By adopting a method for inspecting a semiconductor device by causing a plurality of probes respectively formed on a plurality of beams of a first board of a plurality of electrical connection boards arranged in an inspecting apparatus to be individually brought into direct contact with a plurality of electrode pads of a semiconductor device for inspection while establishing electrical connection therebetween, comprising the step of: effecting electrical inspection while causing each of the probes to wipe a surface of each of the electrode pads of the semiconductor device, a method of contact becomes possible in which scars on the electrode pads are small and a low pressing force is applied, and which gives low damage.
Further, by using the above-described structure and process, even if the electrode pads have oxide films formed thereon with a thickness of several angstroms, it becomes possible to establish reliable contact. Consequently, the inspected semiconductor devices or electronic parts can be provided at very low cost.